The present invention relates to a filter housing for At least one axial flow filter element through which fluid to be filtered flows axially between its axial end faces and which has at least one continuous sealing collar on its outer circumference which can be pressed against a sealing flange on the housing.
German Patent Publication No. DE 32 49 151 C2 discloses an axial flow filter element. The compact filter element disclosed in that document comprises a corrugated and a smooth filter paper. The filter papers are bonded together and then wrapped together to form a filter element of the desired size. Bonding is effected by applying bands of adhesive in the margin such that interspaces between the corrugated and the smooth layer are alternately closed at the two end faces to prevent direct flow through the channels formed between the filter papers. An air stream flowing from the unfiltered air side to the filtered air side flows initially only into a dead-end channel, then through the filter paper and out of a dead-end channel on the other side. Compared to conventional pleated filters, these compact air filters have the advantage of offering either a larger filter surface for the same overall size or the same filter surface for a smaller overall size. The wrapped filter core is formed in such a way that the air can flow only through the filter paper.
In these and other compact air filter elements the flow is axial from one end face to the other. For flawless functioning, it is essential that the compact air filter element is hermetically sealed along its outer circumference in relation to the filter housing. To this end, a sealing collar is circumferentially formed, which must be placed against a corresponding locating shoulder in the filter housing and then pressed against this shoulder.
If the filter surface is to be increased, e.g., to lower the flow resistance, the wrapping diameter of the filter element and thus the filter housing dimensions also increase. There are usually limits to the expansion of the filter housing, however, because of the available installation space. As an alternative, a plurality of small filters with their own filter housings may be operated in parallel, but this is expensive, takes up installation space because of the additionally required inlet and outlet lines and has the result that for servicing the connections on several filter housings must be released, each housing must be opened, the filter elements must be replaced and the connections subsequently reestablished, so that any filter replacement is very labor intensive.